This invention relates to a composition for protecting plants, e.g., seeds of such economically important crops as cotton, peanuts, snap beans, and the like, from phytopathogenic fungi, e.g., such genera of the classes Basidiomycetes and Deuteromycetes as Rhizoctonia, Fusarium, Aspergillus, Penicillium, Ustilago, Tilletia, and so forth. More particularly, the invention herein concerns a composition containing the endospores of a microorganism capable of providing protection from phytopathogenic fungi and a chemical fungicide which is toxic to the microorganism.
The control of phytopathogenic fungi is of great economic importance since fungal growth on plants or on parts of plants, e.g., fruits, blossoms, foliage, stems, tubers, roots, etc., inhibits production of foliage, fruit or seed and reduces the overall quantity and quality of the harvested crop. The continuous economic toll taken by phytopathogenic fungi establishes a continuing need to develop new, more effective fungicides which possess curative, preventative and systemic action to protect cultivated plants and the seeds from which they develop. Those requirements must be accomplished without any significant adverse side effects to the plants of the desired crops.
Compositions containing dried bacteria and agricultural chemicals have been employed to pre-treat or pre-inoculate seeds. However, these compositions have sometimes exhibited reduced bacterial activity over time, presumably as a result of the degradative effects of the chemical component on the biological component. Such compositions have even been found to lack virtually all bacterial activity despite having been formulated with an adequate quantity of bacteria. For this reason, it has been the practice to apply a chemical fungicide such as captan, thiram, carboxin, metalaxyl, quintozene (PCNB), and the like to the seed well in advance of planting, but to only apply Bacillus subtilis endospores, a known seed inoculant (e.g., Quantum-4000.RTM. HB biological inoculant available from Gustafson, Inc., Plano, Tex.), to the seed just before planting on the premise that a reduced period of exposure of the Bacillus subtilis endospores to the chemical fungicide will minimize any loss of bioeffectiveness of the spores.